Diabetes, of which hyperglycemia is a manifestation, is essentially a condition due to a deficient secretion of insulin by the islands of Langerhans; and, according to modern medical nomenclature, should be called hypo-insulinism. Diabetes, or hypo-insulinism, therefore, bears the same relation to the internal secretion of the pancreas that myxedema, or cretinism (hypothyroidism) has to that of the thyroid gland. We know that hypothyroidism is not the only dysfunction of the thyroid gland and that there is a hypersecretion of that important organ, hyperthyroidism, in which there are certain characteristic symptoms; i. e., the syndrome called hyperthyroidism. It has been observed that hyperthyroidism sometimes precedes hypothyroidism. 1 It seems probable that there are other dysfunctions of the islands of Langerhans, besides hypo-insulinism, and that an excessive formation of insulin may occur. Hyperinsulinism should produce definite results, i. e., a reduction in blood sugar, which, when below a certain limit, about